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Invertebrate Zoology Lecture

Annoucements:
INVERTBRATE ZOOLOGY HAS GONE ON-LINE DURING THE SUSPENSION OF CLASSES RESULTING FROM THE CORONA VIRUS PANDEMIC.  Instructions for assignments and 'take-home' quizzes and exams are posted on our class D2L page, not on these pages (however, these pages with lecture links will be maintained).  In lecture, I am enhancing the  lecture readings to supply the material you will use to complete the two remaining lecture exams.  Keep up with the lecture notes as I post them, and stay aware of exam/quiz dates.

Lecture Outlines

Table of content for lectures by phylum via the phylogenetic tree (Prezi version)

(alternative html version)

Study Help

  • Study Help for Mini-exam

    Know "simplified phylogenetic tree".  I will give you the tree with some of the phyla filled in.  You will fill out the rest of the phyla and the names of the major branches (e.g. Ecdysozoa) based on your knowledge of who is most closely related to who.  Know the common names associated with these phyla.  The tree will be arranged differently and I may give you either the type of tree (the HTML version or the Prezi version). Remember, what is important is the order of divergence.

    Students should be able to define:

    • phylogeny 
    • taxon 
    • clade 
    • triploblastic 
    • bilateral symmetry
    • coelom 
    • analogous structures 
    • homologous structures 
    • paraphyletic
    • monophyletic 
    • neotony 
    • Cambrian Explosion
    • evolution
    • natural selection 
    • long branch attraction

    In addition to italicized  questions in the Lecture Outlines, students should be able to:

    • 'Read' a phylogenetic tree (i.e be able to determine which taxa are more closely related to others based on relative differences in time since divergence of shared ancestors). 
    • Recognize what the Lamarck's examination of the invertebrates reveal to him.
    • Compare the old (historical) phylogenetic tree to the more recent Simplified tree  and name one set of characteristics that is no longer used to define major branches of the phylogenetic tree.
    • Explain why organisms that may be more superficially similar in some respects are not always the most closely related.  Explain why organisms that are closely related may not always be similar?
    • Describe the kinds of characters that are considered in each of the three schools of classification, and explain how these different methods of systematics can produce phylogenetic trees that differ from one another.
    • Identify and explain the fields of study that are used  resolve problems associated with determining phylogentic relationships, and explain why don't these fields always yield conclusive results to these problems.  For example, discuss some advantages of and  problems with using molecular sequence data to resolve phylogenies.
    • Be able to distinguish monophyletic and paraphyletic groupings using a phylogenetic tree.
    • Explain why are the Burgess Shale and Chengjiang fossil beds particularly useful in understanding invertebrate phylogentic relationships
    • Explain why the study of Hox genes is useful in understanding phylogentic relationships (i.e. what are the advantages of this approach?).
    • Explain why, despite the fact that various approach for studying phylogenetic relationships can give different answers, do zoologists have confidence in many of these relationships?
    • Describe the four "Early Metazoan Fossil Records" discussed in class and recognize which records are older? 
    • What do trace fossil imply about the body plan of early animals?
    • Identify the general factor that determines the direction of natural selection and relate this to the idea that there is or is not an  "end goal of evolution"?

    Be able to answer questions from these readings:

    • Chapter 1 of textbook:  Be familar with terms in bold face
    • Chapter 2 of textbook, Sections: "Why Determine Evolutionary Trees?", "How Evolutionary Relationships Determined" (up to "Phenetics"), and "Uncertainty about Evolutionary Relationships"
    Practicing questions from the in-class group activities may also be useful:
  • Study Help for Exam I

    Students should be able to identify which phyla are more closely related to others in the phylogenetic tree. Know to which clade a phylum belongs (e.g. rotifers are within the Syndermata clade that is within the broader Gnathifera clade).   Know the evidence that unites phyla on each clade.

    For each phylum (and for the Protozoa), be able to describe morphological characteristics that define each of the phyla.  In doing so, you should provide enough detail to describe the basic appearance of members in that phylum, and to distinguish that phylum from other phyla.  For each class (or protozoan subgroup), be able to match the name of the class to a description of characteristics for that class:

    Protista

    • Rhizaria
    • Alveolates
    • Excavata
    • Unikonta

    Porifera

    • Class Hexactinellida 
    • Class Demospongia 
    • Class Calcarea

    Placozoa

    Cnidaria

    • Class Hydrozoa 
    • Class Scyphozoa 
    • Class Cubozoa 
    • Class Anthozoa

    Ctenophora

    • Class Tentaculata 
    • Class Nuda

    Platyhelminthes

    • Class Trematoda 
    • Class Turbellaria 
    • Class Cestoda

    Mesozoa

    Rotifers

    Acanthocephalans

    Gnathostomulida

    Micrognathoza

    For each phylum above your should also be able to describe its natural history in a general sense.  For example mostly parasitic or free-living, if free-living mostly marine, freshwater, or terrestrial, if aquatic, mostly benthic or planktonic.  Note that some phyla may be variable in their natural history displaying more than one life style.

    Students should be able to define (and be sure to know to which phyla these terms apply):

    • syncytial 
    • planula larva
    • red tides 
    • hermaphroditic 
    • gemmules 
    • spicules 
    • cnidoblasts 
    • mesoglea 
    • statocysts 
    • medusa 
    • polyp 
    • colloblasts 
    • comb rows 
    • ocelli 
    • scolex 
    • proglottids 
    • corona
    • parthenogenesis

    In addition to answering italicized questions in the Lecture Outlines, students should be able to be able to:

    • Be able to apply concepts (such as paraphyletic, homologous, neotony, convergent evolution...) from the introductory lectures to the current lecture material.
    • Explain the purpose of an excretory system and of a circulatory system. Explain how phyla that lack certain systems (e.g. circulatory, excretory, digestive, ...) are able get along without these systems (in general, consider how morphology and physiology reflect natural history of each group).
    • Construct an argument that parasites in general are not 'simple' organisms, and describe the challenges faced by parasites in general in completing their lifecycles.
    • Explain the evidence for why the choanoflagellate protozoans are considered the closest living protist relatives of the animals
    • Describe the life cycle of Plasmodium, the malaria-causing protozoan, and of the parasitic flatworm Schistosoma (you do not have to know the specific names of the parasite stages, but you should know the host organisms,  target organs, and the methods of transmission involved).
    • Discuss evidence that suggests that sponges are the oldest animal phylum and least related (the outgroup) to other animal phlya.
    • Describe and discuss (or draw trees of) the possible phylogenetic relationships of the Placozoa to other phlya.
    • Make an argument that ctenophores and cnidarians are closely related (form a monophyletic grouping).  Make an argument that ctenophores are more closely related to the bilateria phyla than to cnidarians (ctenophores and cnidarians form a paraphyletic group).  
    • Compare the layout of the nervous system in radially symmetrical organisms versus bilaterally symmetrical organisms
    • Discuss evidence for abandoning the traditional  grouping of phyla into aceolomates, pseudoceolmates, and ceolomates.  Provide an alternative on how  aceolomates and pseudoceolmates might have evolved  (i.e. a possible senerio for the evolution of bilateria phyla).  State the type of evidence  for the more recently accepted  grouping of the Platyhelminthes, Mesozoa, Rotifera, Acanthocephala, Gnathostomulida, and Micrognathoza.
    • Explain why simplicity doesn't always imply that a group is an an early (primitive) evolutionary branch (i.e. what selective pressures lead to more simple body plans?).
    • Identify how the rotifers and acanthocephlans differ from the other phyla that were traditionally considered pseudocoelomate.  Identify characteristics that indicate that  rotifers and acanthocephlans are closely related.  Explain what defines the group of phyla known as the Gnathifera.

    Be able to answer questions from these readings: 

    Web link:

    Textbook:

    • Chapter 3 of textbook, Section: "Protozoan Locomotory Systems"
    • Chapter 4 of textbook, Box 4.1 "Histocompatibility in Sponges"
    • Chapter 6 of textbook, Box 6.1 "Control of Nutrient Transfer..."
    • Chapter 7 of textbook, Section: "Introduction and General Characteristics"
    • Chapter 11 of textbook, Box 11.1 "Assessing Phylogenetic Relationships


    Practicing questions from the in-class group activities may also be useful:

  • Study Help for Exam II 

    Be able to identify which phyla are more closely related to others in the phylogenetic tree.  Know to which clade a phylum belongs (e.g. sipunculids are within the Trochozoa clade that is within the broader Lophotrochozoa clade). Know the evidence that unites phyla on each clade.
      
    Be able to describe morphological characteristics that define each of the following phyla.  In doing so, you should provide enough detail to describe the basic appearance of members in that phylum, and to distinguish that phylum from other phyla.  For each class, be able to match the name of the class to a description of characteristics for that class:

    Mollusca 
    • Class Gastropoda
    • Class Bivalvia
    • Class Cephalopoda

    Annelids 

    • Class Polychaeta 
    • Class Clitellata (Oligochaeta and Hirudinea) 
    • Class Pogonophora 
    • Class Echiura

    Sipunculans

    Nemertines

    Phoronids

    Brachiopods

    Bryozoans

    Entoprocts

    Arthropods 

    Subphylum Trilobitomorpha

    • Class Trilobita 

    Subphylum Chelicerata

    • Class Merostomata 
    • Class Arachnida 
    • Class Pycnogonida 

    Subphylum Mandibulata

    • Class Myriapoda 
    • Class Insecta 
    • Class Crustacea 

    Onychophorans

    Tardigrades

    For each phylum above your should also be able to describe its natural history in a general sense.  For example mostly parasitic or free-living, if free-living mostly marine, freshwater, or terrestrial, if aquatic, mostly benthic or planktonic.  Note that some phyla may be variable in their natural history displaying more than one life style.

    Be able to define (and be sure to know to which phyla these terms apply):
    • epitoky
    • setae
    • chitin
    • chemosynthesis
    • trochophore larva
    • open circulatory system
    • radula
    • torsion
    • rhynochocoel
    • lophophore
    • statoblast
    • tagma
    • tracheal system
    • lobopods 
    • cryptobiosis  
    • counter-current system

    Be able to (in addition to italicized  questions in the Lecture Outlines):

    • Explain how body plan and natural history ('life style') are related.  For example, how is complexity of the nervous system related to mode of feeding among the three major classes of molluscs?    How is mode of reproduction (i.e. sexual versus asexual) related to lifestyle (colonial versus solitary)  among the three lophophore phyla? 
    • Describe the features  of the 'smaller classes' of molluscs that might indicate each to be representative of the original 'ancestral' mollusc.
    • Know which taxa are economically important and why.
    • Explain why the pogonophorans and echiurans were traditionally considered as phyla and not classes within the Annelids.
    • Concerning the relationship of molluscs, annelids, and brachiopods, describe the evidence that suggests  molluscs and annelids are most closely related, and the evidence that suggests brachiopods and annelids are most closely related.
    • Know examples of convergent evolution discussed in lecture.
    • Describe the evidence that suggests that arthropods and annelids are closely related as represented in older phylogenetic trees.  What morphological evidence suggested that arthropods and molluscs are closely related? What morphological evidence suggests that arthropods are more closely related to nematodes than to annelids?  Which of these is most accepted based on the molecular sequence data?
    • Describe what morphological evidence suggests that insects are more closely related to crustaceans than to arachnids. What morphological evidence suggests that insects are more closely related to arachnids than to crustaceans?  Today, which scheme is more accepted and what types of evidence have help to resolve this?
    • Compare and contrast the arthropod exoskeleton with the molluscan shell?
    • Name an advantage of the waxy epicuticle in arthropods, and a disadvantage of this structure.
    • Name the reasons why the genus Limulus (the horseshoe crab) attracts so much attention.
    • Provide an explanation for why might arthropods have been so successful.   
    • Provide evidence that onychophorans are closely related to arthropods.
    • Describe a possible fossil intermediate between arthropods and other lobopod phyla such as onychophorans.

    Be able to answer questions from these readings:

    Textbook:
    • Chapter 12 of textbook, Section: "Introduction and General Characteristics"
    • Chapter 15 of textbook: all of it
    • Chapter 19 of textbook, Section: the first part of "Phylum Bryozoa"  

    Practicing questions from the in-class group activities may also be useful:

  • Study Help for Final Exam

    FOR THE NEW MATERIAL (Nematoda through Chordates) 
      
    For the phyla we covered since the last exam, be able to identify which phyla are more closely related to others in the phylogenetic tree.  Know to which clade a phylum belongs(e.g. prapulids  are within the cephaloryncha clade that is within the broader cycloneuralian clade within the ecdysozoan clade).  Know the evidence that unites phyla on each clade.

    For each of these phylum your should also be able to describe its natural history in a general sense.  For example mostly parasitic or free-living, if free-living mostly marine, freshwater, or terrestrial, if aquatic, mostly benthic or planktonic.  Note that some phyla may be variable in their natural history displaying more than one life style.

    Be able to define (and be sure to know to which phyla these terms apply):

    • water vascular system 
    • ossicles 
    • dipleurula larvae 
    • notochord 
    • lorica 
    • eutely
    • introvert
    • mieofauna
    • scalid

    Students should be able to (in addition to answering italicized questions in the Lecture Outlines):

    • Be able to identify the subphylum of Chordata or the class of Echinoderm based on the characteristics discussed in lecture.
    • Be able to discuss the various arguments (hypotheses) concerning possible evolutionary relationships to other phyla for each of the three "phyla of uncertain affiliation".
    • Be able to explain why nematodes are round.  Identify organs/tissues in humans that nematodes parasites target.  Describe one type of infection (of your choosing) in humans caused by nematodes (include information on  the parasites life cycle and the effect to human health).  
    • Provide an example of how nematodes influence human behavior in a way that in increases the chance that the parasite will increase it life cycle.  Explain why  relatively less attention has been paid to the effects of nematode parasites on human health?
    • Provide an explanation for why you think your textbook devotes an entire chapter to those ugly old hemichordates, but only a page or so to the beautiful gastrotrichs. (and the correct answer is not because gastrotrichs are so small).  Provide evidence for specific morphological evidence that support your conclusion.
    • Explain why the name "Hemichordata" is a poor choice of names for this phylum.
    • Provide morphological evidence for including tunicates such as sea pork and sea squirts (urochordates) in the same phylum that we belong to.  Be able to discuss how larval and adult morphologies differ in urochordates, and what this might suggest about the evolution of  body plan in cephalochordates and vertebrates.

    Be able to answer questions from these readings: 

    Web links:
    Textbook:
    • Chapter 21, The Hemichordates

     

    THE COMPREHENSIVE PART

    Some questions will involve broad trends that we have observed over the entire animal phylogenetic tree.  For example, go back through your notes for the semester and find evidence to construct an argument for the following questions that were introduced in the final introductory lecture:

    • Has the rate of evolution of new body plans been constant since the origin of animal life, or has the last 500 million years has been mostly "tinkering" ?
    • Has the rate of speciation and extinction been constant among all body plans (i.e. Do species fall into distinct clusters of organism types or along a continuum of form across the entire animal Kingdom)?
    • Should evolution result as a sequence of linear progress where less complex living phyla represent perfect representatives of past life?
    • Ecologically, does the fossil record indicate that the general types of niches in ecological systems are limited?  (i.e. is there a similarity of fauna ecologically but not taxonomically over the history of animals)?

    I will also give you a phylogenetic tree of all animal phyla (similar to the one on the previous take-home exam).   As on the previous exam, for a given branch (clade) marked by a number on the phylogenetic tree, be able to describe the morphological trait or set of traits that are unique to all the phyla within the clade (i.e. all phyla on that branch of the tree).  In other words, explain why is this group of phyla are represented as being more closely related to each other than to other phyla not included on the branch.

Other Resources

Invertebrates in the News

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